This section provides background information related to the present disclosure. This section is not necessarily prior art.
Various industries use combiners to combine amplified signals to increase power supplied to a load. By way of a non-limiting example, a radio frequency (RF) generator may include multiple RF power amplifiers. Power from the RF power amplifiers may be combined by a combiner and provided to a load, such as a plasma chamber. The combined power drives the plasma chamber to fabricate various components such as integrated circuits, solar panels, compact disks (CDs), digital versatile (or video) discs (DVDs), and the like.
In high frequency (HF) and very high frequency (VHF) frequency environments, combiners may include lossy ferrite transformers, transmission lines, isolation devices, etc. The combiners may be isolated or non-isolated, for example, a Wilkinson type combiner, may be an isolated combiner or non-isolated combiner. Another example of a non-isolated transformer is a lossy ferrite transformer operating in a balanced mode. An isolated combiner has inputs that are isolated from each other via, for example, one or more resistors and/or other isolation devices. A non-isolated combiner has inputs that are not isolated from each other.
Combiners have associated parameters, such as form factors, power density levels, heat generation levels, gain matching errors, phase matching errors, etc. The term “form factor” refers to the volume (height, width and depth) and/or envelope of a combiner. The term “power density” refers to power (e.g. kilowatts) per unit area of a combiner. The gain and phase matching errors refer to matching errors between a combiner and a load when the load has a short circuit and/or an open circuit. A particular application of a combiner may have gain, phase and/or impedance matching requirements. Each of the gain, phase and/or impedance matching requirements may include associated matching error limits.
Form factors, complexity and structures of conventional combiners limit (i) the applications and operating environments in which the combiners can be used and (ii) efficiencies, power outputs, etc. of the combiners. As an example, a power generator may have a power density requirement and/or dedicated maximum chassis volume requirements (e.g., maximum height, width and depth requirements). The power generator may include two or more PAs to meet a desired power output. A combiner may be used to combine outputs of the PAs to provide the required power output. However, the combiner may not be usable if the form factor of the combiner and/or of the PAs results in an overall volume of the power generator exceeding the maximum chassis volume.
Also, structural limitations and operating characteristics of typical combiners can require that PAs be combined in even numbers. For example, a power output requirement of a power generator may necessitate the use of 3 PAs. Since an even number of PAs must be used, 4 PAs are incorporated. The 4 PAs are underpowered to meet the required power output. Use of additional PAs increases size, complexity, costs, heat generation, etc. and decreases efficiency and possible applications and operating environments of a power generator.